SAFETY LAMP. 



415 



A, is a large bell of common air, held by 

 the hand, or suspended by a string. 



B, is a lighted safety lamp, held by an as- 

 sistant within the jar. 



C, An air jar, with cap, stop cock, and 

 tube, filled with carburetted hydrogen, and 

 depressed into the water of the pneumatic 

 cistern, D D, so that by gently turning the 

 key^*, the inflammable gas flows through 

 the tube, mixes with atmospheric air, pene- 

 trates the lamp, and enlarges the flame ; it 

 even fills the whole lamp with a delicate 

 blue or green flame, which ultimately ex- 

 tinguishes the light of the lamp ; but if, 

 when the lamp is nearly extinguished, it be 

 lowered a little, so as to better the condi- 

 tion of the air, it will be rekindled, and 

 then may again be raised into the jar, and 

 so on. Comm. 



Figure and Description from Dr. 



" The lamp is seen within 

 a large glass cylinder upon a 

 stool. The cylinder is close- 

 ly covered by a lid, which 

 will not permit the passage of 

 air between it and the cylin- 

 der, and which is so light as 

 to be easily blown off. Ex- 

 cepting the cage alluded to 

 above, the safety lamp differs 

 not materially from those 

 which are ordinarily used. 

 The upper surface of the re- 

 ceptacle for the oil, forms the 

 bottom of the cage, which is 

 so closely fitted to it, and so 

 well closed every where, as 

 to allow air to have access to 

 the flame only through the 

 meshes of the wire gauze. 

 The cage is enclosed within 

 three iron rods, surmounted 

 by a cap, to which a ring for 

 holding the lamp is attached, 

 as seen in the drawing." 



" If while the lamp is burn- 

 in , as represented in the 



Hare. 



